This invention relates to inchworm linear motors or piezoelectric linear actuators and in particular to designs which address difficulties associated with miniaturization. The prior art is mature, going back to the patent of Evans, U.S. Pat. No. 3,551,764 in which piezoelectric drivers at to repeatedly clamp and alternately drive a shaft. The same function is performed by the patents of Parker--U.S. Pat. No. 3,614,486, May--U.S. Pat. No. 3,902,084, Lange--U.S. Pat. No. 4,709,183, Shibuya--U.S. Pat. No. 4,777,398, Orbach--U.S. Pat. No. 5,027,027, and Mitsuyasu--U.S. Pat. No. 5,053,668, the last being applied to a needle valve. None of this prior art addresses the essential difficulty of miniaturization which is that the clamping driver is typically oriented laterally to the drive direction; when the lateral dimension becomes very small there is not sufficient displacement of the clamping driver to allow a practical clamping. That is, the tolerance required for the device dimensions would then be prohibitively small.